// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/test/histogram_tester.h"

#include <memory>

#include "base/metrics/histogram_macros.h"
#include "base/metrics/histogram_samples.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

using ::testing::ElementsAre;
using ::testing::IsEmpty;

namespace {

const char kHistogram1[] = "Test1";
const char kHistogram2[] = "Test2";
const char kHistogram3[] = "Test3";
const char kHistogram4[] = "Test4";
const char kHistogram5[] = "Test5";

} // namespace

namespace base {

typedef testing::Test HistogramTesterTest;

TEST_F(HistogramTesterTest, Scope)
{
    // Record a histogram before the creation of the recorder.
    UMA_HISTOGRAM_BOOLEAN(kHistogram1, true);

    HistogramTester tester;

    // Verify that no histogram is recorded.
    tester.ExpectTotalCount(kHistogram1, 0);

    // Record a histogram after the creation of the recorder.
    UMA_HISTOGRAM_BOOLEAN(kHistogram1, true);

    // Verify that one histogram is recorded.
    std::unique_ptr<HistogramSamples> samples(
        tester.GetHistogramSamplesSinceCreation(kHistogram1));
    EXPECT_TRUE(samples);
    EXPECT_EQ(1, samples->TotalCount());
}

TEST_F(HistogramTesterTest, GetHistogramSamplesSinceCreationNotNull)
{
    // Chose the histogram name uniquely, to ensure nothing was recorded for it so
    // far.
    static const char kHistogram[] = "GetHistogramSamplesSinceCreationNotNullHistogram";
    HistogramTester tester;

    // Verify that the returned samples are empty but not null.
    std::unique_ptr<HistogramSamples> samples(
        tester.GetHistogramSamplesSinceCreation(kHistogram1));
    EXPECT_TRUE(samples);
    tester.ExpectTotalCount(kHistogram, 0);
}

TEST_F(HistogramTesterTest, TestUniqueSample)
{
    HistogramTester tester;

    // Record into a sample thrice
    UMA_HISTOGRAM_COUNTS_100(kHistogram2, 2);
    UMA_HISTOGRAM_COUNTS_100(kHistogram2, 2);
    UMA_HISTOGRAM_COUNTS_100(kHistogram2, 2);

    tester.ExpectUniqueSample(kHistogram2, 2, 3);
}

TEST_F(HistogramTesterTest, TestBucketsSample)
{
    HistogramTester tester;

    // Record into a sample twice
    UMA_HISTOGRAM_COUNTS_100(kHistogram3, 2);
    UMA_HISTOGRAM_COUNTS_100(kHistogram3, 2);
    UMA_HISTOGRAM_COUNTS_100(kHistogram3, 2);
    UMA_HISTOGRAM_COUNTS_100(kHistogram3, 2);
    UMA_HISTOGRAM_COUNTS_100(kHistogram3, 3);

    tester.ExpectBucketCount(kHistogram3, 2, 4);
    tester.ExpectBucketCount(kHistogram3, 3, 1);

    tester.ExpectTotalCount(kHistogram3, 5);
}

TEST_F(HistogramTesterTest, TestBucketsSampleWithScope)
{
    // Record into a sample twice, once before the tester creation and once after.
    UMA_HISTOGRAM_COUNTS_100(kHistogram4, 2);

    HistogramTester tester;
    UMA_HISTOGRAM_COUNTS_100(kHistogram4, 3);

    tester.ExpectBucketCount(kHistogram4, 2, 0);
    tester.ExpectBucketCount(kHistogram4, 3, 1);

    tester.ExpectTotalCount(kHistogram4, 1);
}

TEST_F(HistogramTesterTest, TestGetAllSamples)
{
    HistogramTester tester;
    UMA_HISTOGRAM_ENUMERATION(kHistogram5, 2, 5);
    UMA_HISTOGRAM_ENUMERATION(kHistogram5, 3, 5);
    UMA_HISTOGRAM_ENUMERATION(kHistogram5, 3, 5);
    UMA_HISTOGRAM_ENUMERATION(kHistogram5, 5, 5);

    EXPECT_THAT(tester.GetAllSamples(kHistogram5),
        ElementsAre(Bucket(2, 1), Bucket(3, 2), Bucket(5, 1)));
}

TEST_F(HistogramTesterTest, TestGetAllSamples_NoSamples)
{
    HistogramTester tester;
    EXPECT_THAT(tester.GetAllSamples(kHistogram5), IsEmpty());
}

} // namespace base
